I'm wondering if this might be related to an Origin issue we're currently tracking. We've been getting reports that the Origin client is popping up and taking focus from other apps while they're running. I'm thinking that Origin might be taking focus away from Apex Legends while the game is running, which could explain why your mouse is behaving strangely in-game.
When you have a chance can you try this workaround for me?
1. Close Origin and its services processes (OriginWebHelperService.exe and OriginClientService.exe).
2. Delete all files in the following 2 folders:
- "C:\ProgramData\Electronic Arts\EA Services\License"
- "C:\Users\\AppData\Local\Electronic Arts\EA Services\License"
3. Start Origin back up
Let me know if your'e still seeing any mouse issues after that. Thanks!
/Kent